Disposable absorbent articles such as infant diapers, training pants, feminine care pads and adult incontinence pads/garments are complex products. These types of articles include multiple components, are made on high speed production lines, need to be cost affordable and most importantly, must perform their intended function. In order to be of the quality expected by consumers, individual articles need to include a complete set of the individual components (e.g. an absorbent pad, pair of leg elastics, pair of containment flaps, etc.). Manufacturing systems have been developed that bring all of the components together in one “web” of materials from which individual articles are formed. The quality of the individual articles is controlled so that each article has the intended components and the components are properly attached to and aligned with each other, with some tolerance for manufacturing variability.
In addition to having all of the functional components, consumers expect absorbent articles to be aesthetic, easy to use and comfortable. With some absorbent articles, particularly infant diapers and training pants, one aspect of the product aesthetics has been graphics. Graphics have been used on different components of the articles in order to label the article's brand, size and fit and to provide pictures that are pleasing to caregivers and to children. For example, graphics have been used on the outer covers and the fastener attachment panels of such articles. In some cases, the graphics are “random”, meaning they have a repeating pattern that may be cut at any point, similar to wallpaper. A “random” graphic typically begins and ends on a component of an article in such a way that one or more graphic images around the periphery of the component are incomplete or “cut off”. More specifically, a graphic may be considered “random” if the component on which the graphic appears may be indiscriminately cut when it is incorporated into the absorbent article. In recent years, the state of the art has developed so that “whole” or “complete” graphics may be provided on individual components of absorbent articles, such as the outer cover and the fastener attachment panel. Such “whole”/“complete”/“intact” graphics are known to those of skill in the art as “registered” graphics. The graphics are referred to as “registered” because the component on which the graphics are printed is registered (during manufacture) with the other components of the article so that the graphics are complete on each individual article.
U.S. Pat. No. 5,286,543 issued on Feb. 15, 1994 to Ungpiyakul et al. describes a method and apparatus for controlling the cutting and placement of components on a moving substrate, where the moving substrate may be a web of materials for forming absorbent articles. U.S. Pat. No. 5,286,543 also describes an article including a backsheet layer, a substantially liquid permeable topsheet layer disposed in an adjacent facing relation with said backsheet layer and an absorbent pad sandwiched between the topsheet and backsheet layers. The article also includes a patch of web material secured to the backsheet layer where the patch includes a reference marker and a set of graphics. The reference marker provides for a selected separating of a set of graphics from a series of interconnected graphic sets. U.S. Pat. No. 5,286,543 describes that the reference marker may include a sequence of dots, dashes or other machine-recognizable patterns. Further, U.S. Pat. No. 5,286,543 describes that the reference marker may include a physical discontinuity, magnetic discontinuity, electrical discontinuity, electromagnetic discontinuity or a combination of such discontinuities. U.S. Pat. No. 5,286,543 also describes that the reference marker can include discrete areas of optical brightener (“OB”) material that define or otherwise indicate the desired boundaries of individual patches of web material. One of the examples of individual patches of web material disclosed in U.S. Pat. No. 5,286,543 is a refastenable tape landing zone. U.S. Pat. No. 5,286,543 discloses that suitable web materials for refastenable tape landing zones include polyester, oriented polypropylene, and unoriented polypropylene.
Additional disclosures relating to registration systems have been made. For example, International Publication Number WO 01/56525 A1 relates to a registration system for phasing simultaneously advancing webs of material having variable pitch lengths. International Publication Number WO 01/56525 A1 describes that the position of preprinted objects on a web of material can be established by sensing a visible timing mark on a part of a web that is later removed, sensing a normally invisible to the human eye registration mark that may or may not remain a part of the final product, or using a grid of sensors to look for a recognized pattern of light diffusion.
Disposable absorbent articles have been sold that have included registered graphics. Kimberly-Clark Corporation (Neenah, Wis.) has sold HUGGIES Supreme disposable diapers and PULL-UPS disposable training pants including registered graphics on the film layers of the outer covers. The registration of graphics on Kimberly-Clark products is performed using a reference marker as described in U.S. Pat. No. 5,286,543. The Procter & Gamble Company (Cincinnati, Ohio) has sold PAMPERS disposable diapers including registered graphics on the film layers of the fastener attachment panels. The registration of graphics on Procter & Gamble products appears to be performed using a reference marker that is a rectangular block of deeper color intensity than the colors surrounding the block. Manufacturers of disposable absorbent articles have also sold products including random graphics. For example, Kimberly-Clark Corporation has sold HUGGIES Ultratrim disposable diapers including random graphics on the pattern unbonded nonwoven material (hereinafter referred to as “PUB nonwoven material”) that forms the fastener attachment panel. The random graphics printed on the PUB nonwoven material of the fastener attachment panel of HUGGIES Ultratrim disposable diapers included multiple colors juxtaposed with each other.
Fibrous nonwoven materials are very different from film and film-like materials in terms of what kind of surface they provide for printing. For example, nonwoven materials have three-dimensional microstructures and therefore, the nonwoven materials present irregular surfaces for printing. Additionally, nonwoven materials are porous and when ink is printed onto the nonwoven materials, the ink may soak through the nonwoven fibers. Nonwoven materials also have inherent irregularity because of variability in the formation of the polymer fibers. When nonwoven fibers are printed on, the ink must coat the individual fibers.
Considering the challenges associated with printing on nonwoven materials, the known techniques for registering printed graphics may not be optimal. For example, in order to provide a discrete area of a reference marker, such as an optical brightener, a relatively intense concentration of the marker material may need to be applied to the nonwoven material, resulting in higher overall product cost.